Subsurface Exolife

TL;DR

This paper explores the potential for life on planets with subsurface oceans, analyzing energy sources, habitability, and the likelihood of biospheres existing in diverse icy worlds, which may be more numerous than rocky habitable planets.

Contribution

It provides a comprehensive assessment of subsurface ocean worlds, including habitability potential, energy sources, and their possible abundance compared to rocky planets.

Findings

Subsurface ocean planets can host diverse habitats.

Energy sources for life are available in these worlds.

Such worlds may outnumber rocky habitable planets.

Abstract

We study the prospects for life on planets with subsurface oceans, and find that a wide range of planets can exist in diverse habitats with ice envelopes of moderate thickness. We quantify the energy sources available to these worlds, the rate of production of prebiotic compounds, and assess their potential for hosting biospheres. Life on these planets is likely to face challenges, which could be overcome through a combination of different mechanisms. We estimate the number of such worlds, and find that they may outnumber rocky planets in the habitable zone of stars by a few orders of magnitude.